import javax.servlet.AsyncContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;


@WebServlet(urlPatterns = "/test", asyncSupported = true)
public class MyAsyncServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        long start = System.currentTimeMillis();
        AsyncContext asyncContext = req.startAsync();//开启异步
        asyncContext.start(new UserService(asyncContext));
        long end = System.currentTimeMillis();
        System.err.println(end - start);
    }
}
